Zebra before 6.4.0 Gossiped Block Drop via Forged Coinbase scriptSig Height

{
  "id": "337bc226ba05a8d171e65ba45b2b3d9decfe5697e8e365409063d0d80ea7786a",
  "url": "https://www.cve.org/CVERecord?id=CVE-2026-109366",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Zebra before 6.4.0 Gossiped Block Drop via Forged Coinbase scriptSig Height",
    "summary": "Zebra before 6.4.0 contains an improper integrity validation vulnerability in the inbound gossip download path that allows unauthenticated peers to force dropping of new blocks without penalty. Attackers can serve a real block with a coinbase scriptSig rewritten to height 1, which keeps the ZIP-244 block hash, triggering a behind-tip drop before consensus validation and delaying tip discovery for mining backends.",
    "evidence": "cve:CVE-2026-109366",
    "products": [
      {
        "name": {
          "value": "zebra",
          "evidence": "/containers/cna/affected/0/product"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-109366",
      "aliases": [
        "CVE-2026-109366"
      ],
      "metrics": [
        {
          "format": "CVSS",
          "cvssV4_0": {
            "version": "4.0",
            "baseScore": 6.3,
            "attackVector": "NETWORK",
            "baseSeverity": "MEDIUM",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N",
            "userInteraction": "NONE",
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "privilegesRequired": "NONE",
            "subIntegrityImpact": "NONE",
            "vulnIntegrityImpact": "NONE",
            "subAvailabilityImpact": "NONE",
            "vulnAvailabilityImpact": "LOW",
            "subConfidentialityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE"
          }
        },
        {
          "format": "CVSS",
          "cvssV3_1": {
            "scope": "UNCHANGED",
            "version": "3.1",
            "baseScore": 3.7,
            "attackVector": "NETWORK",
            "baseSeverity": "LOW",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L",
            "integrityImpact": "NONE",
            "userInteraction": "NONE",
            "attackComplexity": "HIGH",
            "availabilityImpact": "LOW",
            "privilegesRequired": "NONE",
            "confidentialityImpact": "NONE"
          }
        }
      ],
      "affected": [
        {
          "vendor": "ZcashFoundation",
          "product": "zebra",
          "versions": [
            {
              "status": "affected",
              "version": "0",
              "lessThan": "6.4.0",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.4.0",
              "versionType": "semver"
            }
          ],
          "packageURL": "pkg:cargo/zebrad",
          "defaultStatus": "unaffected"
        }
      ],
      "modified": "2026-10-26T20:37:40.885Z",
      "provider": "cve",
      "references": [
        "https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-4f6v-mj46-gxg3",
        "https://www.vulncheck.com/advisories/zebra-before-6.4.0-gossiped-block-drop-via-forged-coinbase-scriptsig-height"
      ],
      "provider_metadata": {
        "adp": [
          {
            "title": "CISA ADP Vulnrichment",
            "metrics": [
              {
                "other": {
                  "type": "ssvc",
                  "content": {
                    "id": "CVE-2026-109366",
                    "role": "CISA Coordinator",
                    "options": [
                      {
                        "Exploitation": "poc"
                      },
                      {
                        "Automatable": "no"
                      },
                      {
                        "Technical Impact": "partial"
                      }
                    ],
                    "version": "2.0.3",
                    "timestamp": "2026-10-26T20:37:04.530681Z"
                  }
                }
              }
            ],
            "references": [
              {
                "url": "https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-4f6v-mj46-gxg3",
                "tags": [
                  "exploit"
                ]
              }
            ],
            "providerMetadata": {
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP",
              "dateUpdated": "2026-10-26T20:37:40.885Z"
            }
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        ],
        "cna": {
          "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
          "shortName": "VulnCheck",
          "dateUpdated": "2026-10-12T16:05:43.620Z"
        }
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-109366",
        "evidence": "/cveMetadata/cveId"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/containers/cna/metrics"
  },
  "source_id": "core-cve",
  "document_id": 344065,
  "published_at": "2026-10-12T16:05:43.62+00:00"
}